Updated: Jan 20, 2021
By now everybody has heard of renewable energy: a list of power sources revolving around the use of resources in a way that can be sustained indefinitely, forgoing fossil fuels necessary for traditional energy production. The most well-known forms of renewable energy are wind power (which is responsible for 20% of the European Union’s total electricity supply), solar energy collection through PV panels (now the least expensive form of energy production), and geothermal sources.
Although our planet is already on track to experience a global average temperature rise of 2°C by the end of the century, divesting from non-renewable energy sources is critical if we as a species are to keep that temperature change below 5°C. A shift that drastic in the Earth’s average global temperature would likely lead to critical harvest failures around the world, famines and mass starvation alongside apocalyptic and irreversible ecological damage.
In order to save our children and grandchildren from this terrible future, it is important that we today embrace renewables of all types, instead of focusing on the implementation of a select few. Diversifying clean sources of electricity will help to lessen the impact that removing fossil fuel-based (and thereby carbon intensive) sources from the grid will have on global energy security. To that end, here are 3 lesser-known forms of renewable energy I recommend be more fully investigated and integrated within our supply leading into the 2020s.
Spearheaded by Carbon Engineering Ltd.’s proof-of-concept plant in Squamish, British Columbia, Direct Air Capture (DAC) presents an ingenious method of energy production as a by-product of the technology's main function. DAC is an emerging technology that focuses on capturing CO2 directly out of the atmosphere, as a way to combat ever-increasing GHG emissions. The interesting part is that the atmospheric CO2 captured this way can be mixed with hydrogen separated out of water, thereby producing a synthetic crude hydrocarbon. This “syncrude” can then be further refined into fuels akin to gasoline or jet fuel, which, importantly, are suitable for use with existing vehicles. Unlike other sources of clean energy, which would require large-scale re-engineering or the development of new battery technologies in order to widely implement, this synthetic hydrocarbon is already almost universally compatible with our existing infrastructure. DAC opens the door to a renewable and by definition carbon-neutral fossil fuel, which has the added benefit of being economically competitive with traditionally sourced oil, as well as equally distributed globally.
Aside from carbon dioxide, potent gases like methane (CH4) are also emitted at a large-scale by the industrial and agriculture sectors, contributing to the greenhouse effect with around 84x the intensity of CO2 over a 20 year period. By recovering food waste and other organic materials before they hit the landfill and gathering them for decomposition in a controlled ‘anaerobic digester’ environment, renewable natural gas (RNG) becomes a possibility. After purifying the biogas received from the decomposition, RNG can be used as a transportation fuel in the exact same way as compressed or liquefied natural gas. The RNG can be processed even further into pipeline-quality fuel, for which the main purpose would be combustion at a combined heat and power plant. As of February 2019, there are approximately 620 operational applications of this electricity generation around the United States, like at the Altamont Landfill in Livermore, California, with future developments planned in Kansas and eastern Texas.
A final little-known form of renewable energy which has seen growing interest in the past few years is ocean thermal energy conversion (OTEC). OTEC is specifically tailored for coastal equatorial regions, as the technology utilizes the ocean’s thermal gradient between colder, deeper ocean water and the warmer, shallow surface water; effectively creating a heat engine capable of generating electricity. Unlike other forms of green power production, such as wind or solar, OTEC can operate continuously, and at a far higher capacity than any other oceanic power sources (like wave power or tidal power). The specifics of OTEC power plants are very similar to other commonplace forms of heat engines, like the classical coal-powered steam engine, which, by exploiting the temperature gradient between high-pressure steam and the cooler water vapor it becomes, pushes a piston and turns a turbine, resulting in usable electricity. Crucially, these power plants have no need for a combustible fuel source, as the necessary temperature gradient of at least 20°C is naturally occuring in large parts of our oceans. While nowhere near as widespread as RNG facilities, working models have been constructed in Hawaii and Hainan, with the world’s only continually-operational plant being located in Japan.
To put it briefly, it is essential that these emerging technologies be evaluated and developed over the course of the coming decade in order to bolster global energy security and help society divest from fossil fuels with the least damage to our increasingly-interdependent economies.
Written by — Josh Kalia
This article originally appeared in an article in Plant for California.